security: tlk: enable CONFIG_TRUSTED_LITTLE_KERNEL

security: tlk: enable CONFIG_TRUSTED_LITTLE_KERNEL

This patch enables CONFIG_TRUSTED_LITTLE_KERNEL option in
tegra21_android_defconfig because it is needed for Android customers
only.

Also, this patch removes unnecessary functions from ote_comms.c as they
are generating linker errors as same function definition is present in
Trusty driver too.

te_restore_keyslots which is a TOS specific function is renamed for both
OSes as {tlk|trusty}_restore_keyslots and caller is updated in a separate
patch.

Bug 1961076
JIRA APTS-1126
Tests Verified locally with testing_client

Change-Id: I5b3b9906c2beb3356dc9b239d02c8c2573866287
Reviewed-on: https://git-master.nvidia.com/r/1531585
GVS: Gerrit_Virtual_Submit
Reviewed-by: Mahesh Lagadapati <mlagadapati@nvidia.com>
Tested-by: Mihir Joshi <mihirj@nvidia.com>
Reviewed-by: Hayden Du <haydend@nvidia.com>